In a semiconductor device represented by a silicon semiconductor, finer structure and high integration have been progressing, depending on market needs of high performance, compact sizing or the like. Along with this trend, high degree of flattening technology corresponding to a fine wiring pattern has become essential. In a manufacturing process of a semiconductor substrate, a CMP process has been introduced, for flattening the surface of a wafer having a metal wiring of, for example, a tungsten wiring or the like, by using a polishing slurry containing polishing fines such as, for example, silica or alumina.
In such the CMP process, the polishing fines (particle) such as silica or alumina used in the CMP process, or metal impurities (metal residue) derived from a polished metal wiring, or the like, tend to remain on the surface of the semiconductor substrate (wafer) after polishing. Because these residues affect adversely on electric characteristics of a semiconductor, such as short-circuit between wirings, it is necessary to remove these residues by cleaning the semiconductor substrate (wafer), after the CMP process.
Conventionally, as a cleaning method after the CMP process, there have been known a cleaning method of a semiconductor substrate (wafer), using a cleaning agent combined with a hydrofluoric acid aqueous solution and hydrogen peroxide/ammonia aqueous solution, or a cleaning agent combined with a hydrofluoric acid aqueous solution and hydrogen peroxide hydrochloric acid. However, such the method has become not applicable to a recent wiring formation process, where finer wiring has progressed, because the corrosion to the metal wiring is fierce.
As a method for solving a problem of this corrosion property, there has been proposed a cleaning process using a cleaning agent containing an organic acid such as citric acid or oxalic acid, which have less corrosive property to a metal wiring, and a chelating agent such as amino polycarboxylic acids (for example, Patent Literature 1 or the like). In addition, as a cleaning process of a semiconductor substrate provided a copper wiring on a substrate of a surface, there has been proposed a cleaning process using a cleaning agent containing a compound having a nitrogen atom with an unshared electron pair in a molecule (for example, Patent Literature 2 or the like). Further, as a cleaning process for removing impurities derived from a metal on a substrate of a surface, there has been proposed a cleaning method using an alkaline cleaning agent containing a chelating agent such as an amino polyphosphonic acid and an alkaline compound (for example, Patent Literature 3 or the like), or a purification method using a composition containing a carboxylic acid, a compound containing an amine and phosphonic acid (for example, Patent Literature 4 or the like), or the like. Still further, as a cleaning process of a semiconductor substrate, in which a tungsten wiring or a tungsten alloy wiring are formed on a substrate of a surface, there has been proposed a cleaning method using a neutral or an alkaline cleaning agent containing an organic amine, a quaternary ammonium hydroxide and a chelating agent (for example, Patent Literature 5 or the like).